1. Field of the Invention
The invention relates to a door fixture to be fastened to a frame of an isolator, comprising a door and a double bayonet closure comprising two bayonet locks of different chiralities for the purpose of reciprocally transferring the isolator from a first state, in which the door, which opens from inside the isolator, is open and detached from the isolator frame and a container flange surrounding a container is sealingly locked to the isolator frame, and a second state, in which the door is shut and sealingly locked to the isolator frame and the flange is detached from the isolator frame, there being provided a first safety device, which allows the door to be opened only when a container flange of a container is sealingly locked to the isolator frame, and a second safety device, which allows the removal of the container flange from the isolator frame only when the door is sealingly locked to the isolator frame.
2. The Prior Art
Door fixtures of the kind described above are known in the prior art in a variety of embodiments, all of which function in the same or similar manner. The known isolator doors generally comprise a door fixed to a frame by a hinge, in which case the door contains a bayonet lock which allows an alternating disk that closes the opening of a flange to be securely attached to the door during an opening operation while being detached from the flange by means of a second bayonet lock, which alternating disk is reversibly detachable from the door when it is in the open condition. When the door is closed by manual operation with the aid of protective gloves that reach into the isolator interior, the door is first securely attached to the isolator frame by means of a latch, whereupon a corresponding backward turn of the handles that are fixed to the flange, with the aid of the double bayonet closure, causes, on the one hand, the alternating disk to be simultaneously detached from the door and attached to the flange, and, on the other hand, the flange to be detached from the frame of the door, whereupon the alternating disk is securely re-attached to the flange such that the flange opening is re-closed.
By virtue of the fact that, in the double bayonet of the known door fixtures, the two bayonet locks have different chiralities i.e. one lock is provided with a right-handed thread and the other lock is provided with a left-handed thread, turning the handles attached to the flange will cause the double bayonet to fulfill the double function of attaching the flange to the frame while detaching the alternating disk from the frame and attaching the alternating disk to the door, and accordingly, when the functions are reversed, detaching the flange from the frame while the alternating disk shifts from being attached to the door to being attached to the flange.
However, when the known double bayonet is used on an isolator, two function-dependent crucial weaknesses emerge in connection with the above described functionality, and these must be avoided at all costs. The first relates to a situation of the isolator in which the door must be opened in the absence of a container, and the second relates to a situation of the isolator in which the container must be removed from the frame with the door open.